ext 图片预览事件触发以及IE7下预览图片

首先在FormPanel里添加图片预览区以及图片选择组件

        /**
 	 * 图片上传区
 	 */
 	this.imageUploadForm = new Ext.form.FormPanel({
 		region: 'east',
 		fileUpload: true,
 		width: 300,
 		split: true,
 		defaultType: 'textfield',
 		bodyStyle: 'align: center;',
 		defaults:{
 			hideLabel: true
 		},
 		items:[{
// 			labelSeparator: '',
 			id:'browseImage',
 			autoCreate:{
 				tag: 'input',
 				type: 'image',
 				src: Ext.BLANK_IMAGE_URL,
                style:'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);'
 				name: 'imageBrowse'
 			}
 		},{
 			inputType: 'file',
 			id: 'imageUpload',
 			cls: 'upst'
 		}]
 		
 	});

接下来添加选择完图片后的change事件

Global.img_reg=/\.([jJ][pP][gG]){1}$|\.([jJ][pP][eE][gG]){1}$|\.([gG][iI][fF]){1}$|\.([pP][nN][gG]){1}$|\.([bB][mM][pP]){1}$/
    /**
 	 *  浏览改变事件
     *  只有当imageUploadForm render后Ext.get('imageUpload')才有效
 	 */
 	this.imageUploadForm.on('render',function(f){
 		this.imageUploadForm.form.findField('imageUpload').on('render',function(){
	 		Ext.get('imageUpload').on('change',function(field,newValue,oldValue ){
	 			var url = 'file:///'+Ext.get('imageUpload').dom.value;
           if(Global.img_reg.test(url)){
								
								if(Ext.isIE7){
		var image = Ext.get('imageBrowse').dom;
image.src = Ext.BLANK_IMAGE_URL;//覆盖原来的图片
image.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src= url;
								}else{
									Ext.get('imageBrowse').dom.src = url;
								}
							}
	 				 		},this);
 		},this);
 	},this);